Any well defined set (group) of objects about which astatistical enquiry is being made is called a population or universe.The total number of objects (individuals or members) in apopulation is known as the size of the population whichmay be finite or infinite.The population can refer to things as well as people.For example,All members of the cultural society of your city.All students of mathematics of Ithaca college.All Americans who saw 'TITANIC' last year.Heights of all students of your school.Weights of all the citizens of city of Lucknow above 20years of age.Mileages of automobiles tyre of Dunlop. etc

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Sample

A finite set of objects drawn from the population with an aim iscalled a sample.Even in every day life we make many of our decisions based onsamples taken, though we are not aware of it. I met Jacksonyesterday first time for an hour or two, I concluded that "Jackson iscrazy" which may be wrong.We just take a little from a gunny bag of rice, we judge its quality andthen we purchase the whole bag.If we want to taste milk, we just take a glassful of milk from the canand taste it.Note that taking a sample is easy in many cases where thepopulation is uniform or homogeneous. When the population isheterogeneous (not uniform), the selection of a sample is not veryeasy.